The present invention relates to an improved gate mechanism for a feed conveyor of the type which cyclically moves goods along the feed conveyor to a tubular discharge member. More particularly, this invention relates to a gate mechanism having a rotatable tubular discharge member with a gate discharge opening and particularly adapted for the transport and discharge of fragile goods.
Various types of gate mechanisms have been devised for particular types of conveyors. Conveyors with a generally tubular construction, such as screw conveyors and conveyors of the type disclosed in U.S. Pat. No. 3,586,155, may employ a rotary gate mechanism to either allow product to discharge through the opened gate or to move product downstream from the closed gate. Various types of rotary gate mechanisms are disclosed in U.S. Pat. Nos. 1,401,155, 3,074,534, 3,077,975, and 3,342,315. U.S. Pat. No. 4,023,675 discloses a slide door for use with a chain conveyor. U.S. Pat. No. 3,731,787 discloses a slide gate with sensors.
An increasingly common type of conveyor utilizes a substantial planar tray floor and a cyclically powered drive mechanism cyclically powered to move the goods along the tray floor. One type of conveyor which utilizes such a cyclically powered tray is a vibratory conveyor, and another type of conveyor which uses a similar cyclically powered tray is a linear motion conveyor. Both vibrating and linear motion conveyors commonly employ substantially planar tray floor with opposing sides, and thus are sometimes referred to as a trough-type conveyor. The stroke in a vibratory conveyor is relatively short, and typically is approximately {fraction (1/16)}th of an inch, so that the tray imparts an upward and forward motion to the goods. The tray is returned to its original position while the goods are out of contact with the tray floor. A linear motion conveyor has a much longer stroke, typically in the range of approximately an inch and a half, and moves the goods slowly forward and returns the tray quickly while the goods slide along the tray floor. A slide gate for a trough-type conveyor is disclosed in U.S. Pat. No. 2,716,741. More complex and specialized types of gates for conveyors with a planar tray floor are disclosed in U.S. Pat. Nos. 3,042,360, 3,315,792, and 3,511,303.
Conventional gate mechanisms for conveyors with a planar tray floor have various problems which have limited their acceptance in the industry. Traditional gate mechanisms are intended to operate in the fully opened or fully closed position. This limitation prevents equipment downstream from the conveyor from receiving a steady flow of product, and thus results in poor production efficiency. Some conveyor manufacturers have attempted to overcome this problem by utilizing triangular shaped cutouts in the conveyor floor and allowing the gate mechanism to be positioned at selected intervals between the fully opened and fully closed position. The use of such triangular shaped cutouts requires a great deal of space along the length of the conveyor, and also requires a linear actuator which is capable of sliding the gate over a relatively long movement.
A significant problem with slide type gate mechanisms for trough-type conveyors with a planar tray floor involves the inability of a gate to completely seal in the closed position. Trough-type conveyors are commonly used to transport snack foods and fine particles associated with such goods have caused a growing problem when high hygiene is critical. Some companies have required specialized devices to prevent unwanted particles, such as dust associated with a transported goods, from leaking out of a closed gate and into another product line. Many slide gates associated with trough-type conveyors have a difficult time sealing the gate area when in the closed position because product is passing through a gate while it is being closed. The product may thus become jammed in the gate sealing area, resulting in both product breakage and the buildup of material to prevent complete gate closing. A related problem is that the gate seal is commonly exposed to the product when the gate is partially or fully opened. As the product passes by the gate seal, the sealing material is worn and thus prevents a reliable seal from substantially being formed when the gate is in the closed position.
The disadvantages of the prior art are overcome by the present invention, and an improved gate mechanism is hereinafter disclosed for a trough-type conveyor. The gate mechanism of the present invention is positioned over the conveyor and may be used on either vibratory conveyors or horizontal motion conveyors. The improved gate mechanism has minimal parts to provide a long life and a reliable operation.
The gate structure or mechanism of the present invention is particularly suited for use with a conveyor for moving fragile goods along an elongate tray and includes a rotary gate mechanism mounted along the conveyor. A powered drive mechanism operatively connected to the tray is effective for cyclically moving fragile goods along the conveyor and the discharged goods may move along a similarly powered downstream tray. The gate mechanism of the present invention comprises a one-piece circular discharge tube or member with a gate discharge opening formed about 120 degrees of the circumference of the circular discharge tube. The circular discharge tube is positioned over the downstream tray and is rotated to a desired position. When the opening is at its lowermost centered position, the entire volume of the goods being transported may be discharged through the gate opening onto the tray. When the opening is positioned at its uppermost centered position by rotation of the circular discharge tube, the entire volume of goods being transported along the circular discharge tube move past the gate discharge opening and no goods are discharged through the gate discharge opening onto the lower tray. As a result, the entire volume of goods is discharged from the downstream end of the circular discharge tube onto another downstream conveyor. The circular discharge tube may be rotated to any desired intermediate position for discharging any desired percent or proportion of the goods and thereby provide a desired volume of goods on each of the downstream trays. The goods moving past the gate discharge opening may be discharged from the downstream end of the circular discharge tube onto the second downstream conveyor.
A powered drive mechanism is operatively connected to the circular discharge tube for reciprocating the circular discharge tube for movement of the goods along the circular discharge tube and either into or past the gate discharge opening. The driving mechanism relies on the reciprocation of the discharge tube for transport of the goods along the circular discharge tube. As indicated, the gate discharge opening may be positioned by selective rotation of the circular discharge tube to any desired position for discharging all or a desired portion of the goods onto the tray. Sensors may be provided along the length of the conveyor to sense the depth of the goods discharged onto the conveyor and data from the sensors may be processed by a computer to control the rotation of the circular discharge tube to a desired position of the gate discharge opening for controlling the volume of goods being discharged through the gate discharge opening.
An object of the invention is to provide a simple gate mechanism which may be easily assembled and disassembled from a location over the tray of a subjacent conveyor on which goods are discharged from a gate discharge opening.
It is a further object to provide a gate mechanism for a conveyor which minimizes damage to goods transported by the conveyor during discharge of the goods onto the conveyor from a gate opening in a circular discharge tube or member.
An additional object is the provision of such a gate mechanism which may be easily mounted over the conveyor without any changes or modifications in the conveyor thereby to provide a simplified hook up or connecting procedure for the gate mechanism which is easily utilized with existing cyclically powered conveyors.
Still another object of the invention is to provide a one-piece circular discharge tube for the discharge of fragile goods from a discharge opening in the discharge tube onto a conveyor having a cyclically movable tray with a tray floor to receive the goods.
A feature of the invention is to provide a circular discharge tube over a conveyor for the discharge of fragile goods from an opening in the discharge tube in which the movement of the goods along the circular discharge tube is obtained by reciprocation of the circular discharge member and without any separate member required for movement of the goods along the circular discharge tube for discharge from the discharge opening in the circular discharge tube.
It is a feature of the present invention that the gate mechanism may be used with either a vibratory conveyor or linear motion conveyor. A related feature of the invention is that the gate discharge mechanism is well suited for use with trough-type conveyors used in the food processing industry. Another feature of the invention is that the gate discharge mechanism may be easily and reliably controlled upon rotation of the circular discharge tube or member to regulate the partial discharge of goods from the circular discharge tube onto the tray of a subjacent conveyor. Yet another feature of the invention is that the gate discharge mechanism may be easily assembled and disassembled without any modification of the conveyor.
A significant advantage of the present invention is that the gate discharge mechanism is simple and utilizes only a single circular discharge tube or member. Such an arrangement is highly reliable and is provided at a relatively low cost with a long life.
These and further objects, features, and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings.